Apparatus and method for driving backlight of liquid crystal display apparatus

ABSTRACT

A backlight driving apparatus of a liquid crystal display (LCD) apparatus including a master trans and a slave trans for supplying a current to a plurality of lamps, and a master driver and a slave driver for driving the lamps, includes an operated condition unit that converts an AC voltage generated in accordance with a phase difference between a master AC voltage and a slave AC voltage fed back from the master trans and the slave trans, respectively, into an analog DC voltage; a protect controller that determines an error is generated during an operation of the lamps using the analog DC voltage and outputs an operating error signal when an error is generated; and a lamp driving controller that stops driving the master driver and the slave driver in response to the operating error signal.

This application claims the benefit of Korean Patent Application No.P2006-0033604, filed on Apr. 13, 2006 and No. P2006-0108859 Nov. 6,2006, which is hereby incorporated by reference for all purposes as iffully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display (LCD)apparatus, and more particularly to a backlight driving apparatus of anLCD apparatus and method for driving the same that are adaptive forautomatically shielding a voltage supply upon generation of an errorduring an operation of lamps.

2. Discussion of the Related Art

Generally, liquid crystal display (LCD) apparatus control the lighttransmittance of liquid crystal cells in accordance with video signalsto display images. Active matrix type LCD apparatus are advantageous forimplementation of moving images because a switching device activelycontrols each liquid crystal cell. A thin film transistor (hereinafter,referred to as “TFT”) is mainly employed for the switching device inactive matrix type LCD apparatus.

FIG. 1 is an equivalent circuit diagram of a pixel of an LCD apparatusaccording to the related art.

Referring to FIG. 1, the LCD converts a digital input data into ananalog data voltage on the basis of a gamma reference voltage to supplyit to a data line DL and, at the same time, supplies a scanning pulse toa gate line GL to thereby charge a liquid crystal cell Clc.

A gate electrode of the TFT is connected to the gate line GL while asource electrode thereof is connected to the data line DL. Further, adrain electrode of the TFT is connected to a pixel electrode of theliquid crystal cell Clc and to one electrode of a storage capacitor Cst.

A common electrode of the liquid crystal cell Clc is supplied with acommon voltage Vcom. The storage capacitor Cst stores a data voltage fedfrom the data line DL when the TFT is turned on to maintain the datavoltage for the liquid crystal cell Clc.

When the scanning pulse is applied to the gate line GL, the TFT isturned on to provide a channel between the source electrode and thedrain electrode thereof, thereby supplying a data voltage on the dataline DL to the pixel electrode of the liquid crystal cell Clc. Thealignment of the liquid crystal molecules of the liquid crystal cellchanges in accordance with an electric field generated between the pixelelectrode and the common electrode and light incident to the LCDapparatus can thus be modulated to display images.

A configuration of an LCD apparatus according to the related art willnow be described. FIG. 2 is a block diagram illustrating a configurationof an LCD apparatus according to the related art.

Referring to FIG. 2, the LCD apparatus 100 includes an LCD panel 110provided with a thin film transistor (TFT) located adjacent to eachcrossing of data lines DL1 to DLm and gate lines GL1 to GLn for eachliquid crystal cell Clc, a data driver 120 for supplying data voltagesto the data lines DL1 to DLm, a gate driver 130 for supplying scanningpulses to the gate lines GL1 to GLn, a gamma reference voltage generator140 for generating gamma reference voltages and supplying them to thedata driver 120, a backlight assembly 150 for irradiating light onto theLCD panel 110, an inverter 160 for applying AC voltages and currents tothe backlight assembly 150, a common voltage generator 170 forgenerating a common voltage Vcom and supplying it to the commonelectrode of the liquid crystal cell Clc, a gate driving voltagegenerator 180 for generating a gate high voltage VGH and a gate lowvoltage VGL and supplying them to the gate driver 130, and a timingcontroller 190 for controlling the data driver 120 and the gate driver130.

The LCD panel 110 has a liquid crystal between two glass substrates. Onthe lower glass substrate of the LCD panel 110, the data lines DL1 toDLm and the gate lines GL1 to GLn perpendicularly cross each other. TheTFTs are provided adjacent to crossings of the data lines DL1 to DLm andthe gate lines GL1 to GLn. The TFTs supply data voltages from the datalines DL1 to DLm to the liquid crystal cells Clc in response to thescanning pulses. The gate electrodes of the TFTs are connected to thegate lines GL1 to GLn while the source electrodes thereof are connectedto the data lines DL1 to DLm. Further, the drain electrodes of the TFTsare connected to the pixel electrodes of the liquid crystal cells Clcand to the storage capacitors Cst.

The TFTs are turned on in response to the scanning pulses applied to thegate terminal thereof via the gate lines GL1 to GLn. Upon turning-on ofthe TFTs, data voltages on the data lines DL1 to DLm are supplied to thepixel electrodes of the liquid crystal cells Clc.

The data driver 120 supplies data voltages to the data lines DL1 to DLmin response to a data driving control signal DDC from the timingcontroller 190. Further, the data driver 120 samples and latches digitalvideo data RGB fed from the timing controller 190, converts them intoanalog data voltages capable of expressing gray scale levels at theliquid crystal cells Clc on the basis of gamma reference voltagesgenerated from the gamma reference voltage generator 140, and thensupplies them to the data lines DL1 to DLm.

The gate driver 130 sequentially generates scanning pulses (gate pulses)in response to a gate driving control signal GDC and a gate shift clockGSC from the timing controller 190 and supplies them to the gate linesGL1 to GLn. The gate driver 130 determines a high-level voltage and alow-level voltage of the scanning pulses in accordance with the gatehigh voltage VGH and the gate low voltage VGL from the gate drivingvoltage generator 180.

The gamma reference voltage generator 140 receives a highest-level powervoltage VDD to generate positive and negative gamma reference voltagesand outputs them to the data driver 120.

The backlight assembly 150 is provided at the rear side of the LCD panel110 and radiates light toward the LCD panel 110 by alternating currentAC voltages and currents supplied from the inverter 160.

The inverter 160 converts a rectangular wave signal generated at theinterior thereof into a triangular wave signal, compares the triangularwave signal with a direct current DC power voltage VCC supplied from theLCD apparatus, and then generates a burst dimming signal based on theresult of the comparison. In response to the burst dimming signal, adriving integrated circuit IC (not shown) in the inverter 160 controlsthe AC voltages and currents supplied to the backlight assembly 150.

The common voltage generator 170 receives a high-level power voltage VDDto generate a common voltage Vcom, and supplies it to the commonelectrode of the liquid crystal cell Clc provided at each pixel of theLCD panel 110.

The gate driving voltage generator 180 is supplied with a high-levelpower voltage VDD to generate the gate high voltage VGH and the gate lowvoltage VGL, and supplies them to the data driver 130. Herein, the gatehigh voltage VGH is greater than the threshold voltage of the TFTprovided at each pixel of the LCD panel 110 and the gate low voltage VGLis less then the threshold voltage of the TFT. The gate high voltage VGHand the gate low voltage VGL generated in this manner are used fordetermining a high-level voltage and a low-level voltage of the scanningpulses generated by the gate driver 130, respectively.

The timing controller 190 supplies digital video data RGB from a digitalvideo card (not shown) to the data driver 120 and, at the same time,generates a data driving control signal DCC and a gate driving controlsignal GDC using horizontal/vertical synchronizing signals H and V inresponse to a clock signal CLK to supply them to the data driver 120 andthe gate driver 130, respectively. Herein, the data driving controlsignal DDC includes a source shift clock SSC, a source start pulse SSP,a polarity control signal POL and a source output enable signal SOE,etc. The gate driving control signal GDC includes a gate start pulse GSPand a gate output enable signal GOE, etc.

A configuration of the related art backlight driving apparatus includedin a backlight assembly of an LCD apparatus having the above-mentionedconfiguration will now be described.

FIG. 3 is a block diagram illustrating a configuration of a backlightdriving apparatus of an LCD apparatus according to the related art.

Referring to FIG. 3, the backlight driving apparatus 200 includes a lampdriving controller 202, a master driver 203, a slave driver 204, amaster AC/DC switching portion 205, a slave AC/DC switching portion 206,a master trans 207 and a slave trans 208.

The lamp driving controller 202 generates a push-pull gate signal forcontrolling a plurality of lamps 201 in accordance with the burstdimming signal.

The master driver 203 and the slave driver 204 generate a pull-bridgegate signal for the plurality of lamps 201 in response to the push-pullgate signal.

The master DC/AC switching portion 205 switches converts a DC high-levelvoltage DC 400V inputted from the master driver 203 in accordance withthe pull-bridge gate signal to an AC voltage 400 Vrms, and supplies apositive AC voltage 400 Vrms and a negative AC voltage 400 Vrms to themaster trans 207 via each two signal lines.

The slave DC/AC switching portion 206 converts a DC high-level voltageDC 400V inputted from the slave driver 204 in accordance with thepull-bridge gate signal to an AC voltage 400 Vrms, and supplies apositive AC voltage 400 Vrms and a negative AC voltage 400 Vrms to theslave trans 208 via each two signal paths. The master DC/AC switchingportion 205 and the slave DC/AC switching portion 206 output the ACvoltages 400 Vrms having the same phase.

The master trans 207 boosts the AC voltage 400 Vrms inputted, via twosignal lines, from the master DC/AC switching portion 205 to an ACvoltage 750 Vrms and supplies it to an edge of the plurality of lamps201. The slave trans 208 boosts the AC voltage 400 Vrms inputted, viatwo signal lines, from the slave DC/AC switching portion 206 to an ACvoltage 750 Vrms and supplies it to the other edge of the plurality oflamps 201. The AC voltage 750 Vrms outputted from the slave trans 206has an adverse phase to the AC voltage 750 Vrms outputted from themaster trans 207.

Thus, the AC voltages 750 Vrms having adverse phases are supplied to theboth edges of the plurality of lamps 201. As a result, the AC voltage1500 Vrms is substantially supplied to the plurality of lamps 201. Themagnitude of the AC voltage supplied to the lamps 201 may changedepending upon the type and number of the lamps.

As described above, the related art backlight driving apparatus does nothave an error detection function so that an inspector or customer may besubject to an electrical shock.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a backlight drivingapparatus of an LCD apparatus and method for driving the same thatsubstantially obviates one or more problems due to limitations anddisadvantages of the related art.

An advantage of the present invention is to provide a backlight drivingapparatus and method for driving the same that are adaptive forautomatically shielding a voltage supply upon generating of an errorduring an operation of lamps.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. These andother advantages of the invention will be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, a backlightdriving apparatus of a liquid crystal display (LCD) apparatus includinga master trans and a slave trans for supplying a current to a pluralityof lamps, and a master driver and a slave driver for driving the lamps,includes an operated condition unit that converts an AC voltagegenerated in accordance with a phase difference between a master ACvoltage and a slave AC voltage fed back from the master trans and theslave trans, respectively, into an analog DC voltage; a protectcontroller that determines an error is generated during an operation ofthe lamps using the analog DC voltage and outputs an operating errorsignal when an error is generated; and a lamp driving controller thatstops driving the master driver and the slave driver in response to theoperating error signal.

The invention, in a method of driving a backlight driving apparatus ofthe LCD apparatus including a master trans and a slave trans forsupplying a current to a plurality of lamps, and a master driver and aslave driver for driving the lamps, comprises the steps of converting aAC voltage generated by a phase difference of a master AC voltage and aslave AC voltage fed back from the master trans and the slave trans intoan analog DC voltage; judging a generation of an error of the lampsoperated by using the analog DC voltage to generate an operating errorsignal and the enable signal in accordance with the result; and stoppinga drive of the master driver and the slave driver in response to anoperating error signal from the protective controller or for normallydriving the master driver and the slave driver in response to the enablesignal of the protective controller. Herein, the present inventionfurther includes the steps of converting a master AC voltage fed backfrom the master trans into a master DC voltage and converting a slave ACvoltage fed back from the slave trans into a slave DC voltage; judgingan initial error generation of the lamps using the fed back master DCvoltage and the slave DC voltage at an initial driving condition andgenerating an initial error signal and the enable signal in accordancewith the result; and stopping an initial drive of the master driver andthe slave driver in response to the initial error signal.

The present invention, in a backlight driving apparatus of the LCDapparatus including a master trans and a slave trans for supplying acurrent to a plurality of lamps, and a master driver and a slave driverfor driving the lamps, comprises a voltage feedback means for convertinga master AC voltage fed back from the master trans into a master DCvoltage and for converting a slave AC voltage fed back from the slavetrans into a slave DC voltage; a protective controller for judging aninitial error generation of the lamps using the fed back master DCvoltage and the slave DC voltage at an initial driving condition togenerate an initial error signal and the enable signal in accordancewith the result; and a lamp driving controller for stopping an initialdrive of the master driver and the slave driver in response to aninitial error signal from the protective controller or for normallydriving the master driver and the slave driver in response to the enablesignal from the protective controller.

The present invention, in a method of driving a backlight drivingapparatus of the LCD apparatus including a master trans and a slavetrans for supplying a current to a plurality of lamps, and a masterdriver and a slave driver for driving the lamps, comprises the steps ofconverting a master AC voltage fed back from the master trans into amaster DC voltage and converting a slave AC voltage fed back from theslave trans into a slave DC voltage; judging an initial error generationof the lamps using the fed back master DC voltage and the slave DCvoltage at an initial driving condition and generating an initial errorsignal and the enable signal in accordance with the result; and stoppingan initial drive of the master driver and the slave driver in responseto the initial error signal from the protective controller or fornormally driving the master driver and the slave driver in response tothe enable signal from the protective controller.

The present invention, in a backlight driving apparatus of the LCDapparatus including a master trans and a slave trans for supplying acurrent to a plurality of lamps, and a master driver and a slave driverfor driving the lamps, comprises an operating condition detect means forconverting a AC voltage generated by a phase difference of a master ACvoltage and a slave AC voltage fed back from the master trans and theslave trans into an analog DC voltage; and a main control means forjudging a generation of an error of the lamps operated by using theanalog DC voltage to stop a drive of the master driver and the slavedriver or to normally drive the master driver and the slave driver inaccordance with the result. Herein, the present invention furtherincludes a voltage feedback means for converting a master AC voltage fedback from the master trans into a master DC voltage and for converting aslave AC voltage fed back from the slave trans into a slave DC voltageto output it to the protective controller.

The present invention, in a method of driving a backlight drivingapparatus of the LCD apparatus including a master trans and a slavetrans for supplying a current to a plurality of lamps, and a masterdriver and a slave driver for driving the lamps, comprises the steps ofconverting a AC voltage generated by a phase difference of a master ACvoltage and a slave AC voltage fed back from the master trans and theslave trans into an analog DC voltage; and judging a generation of anerror of the lamps operated by using the analog DC voltage to stop adrive of the master driver and the slave driver or to normally drive themaster driver and the slave driver in accordance with the result.

The present invention, in a backlight driving apparatus of the LCDapparatus including a master trans and a slave trans for supplying acurrent to a plurality of lamps, and a master driver and a slave driverfor driving the lamps, comprises a voltage feedback means for convertinga master AC voltage fed back from the master trans into a master DCvoltage and for converting a slave AC voltage fed back from the slavetrans into a slave DC voltage; and a main control means for judging aninitial error generation of the lamps using the fed back master DCvoltage and the slave DC voltage at an initial driving condition to stopan initial drive of the master driver and the slave driver or tonormally drive the master driver and the slave driver in accordance withthe result.

The present invention, in a method of driving a backlight drivingapparatus of the LCD apparatus including a master trans and a slavetrans for supplying a current to a plurality of lamps, and a masterdriver and a slave driver for driving the lamps, comprises the steps ofconverting a master AC voltage fed back from the master trans into amaster DC voltage and for converting a slave AC voltage fed back fromthe slave trans into a slave DC voltage; and judging an initial errorgeneration of the lamps using the fed back master DC voltage and theslave DC voltage at an initial driving condition to stop an initialdrive of the master driver and the slave driver or to normally drive themaster driver and the slave driver in accordance with the result.

The present invention, in a backlight driving apparatus of the LCDapparatus including a master trans and a slave trans for supplying acurrent to a plurality of lamps, and a master driver and a slave driverfor driving the lamps, comprises an operating condition detect means forconverting a AC voltage generated by a phase difference of a master ACvoltage and a slave AC voltage fed back from the master trans and theslave trans into an analog DC voltage: a protective controller forjudging an error generation of the operating lamps using the analog DCvoltage to stop a drive of the master driver and the slave driver or tonormally drive the master driver and the slave driver in accordance withthe result; and a lamp driving controller for controlling an output ofthe master driver and the slave driver in accordance with the inputtedburst dimming signal. Herein, the present invention further includes avoltage feedback means for converting a master AC voltage fed back fromthe master trans into a master DC voltage and for converting a slave ACvoltage fed back from the slave trans into a slave DC voltage to outputit to the protective controller.

The present invention, in a method of driving a backlight drivingapparatus of the LCD apparatus including a master trans and a slavetrans for supplying a current to a plurality of lamps, and a masterdriver and a slave driver for driving the lamps, comprises the steps ofconverting a AC voltage generated by a phase difference of a master ACvoltage and a slave AC voltage fed back from the master trans and theslave trans into an analog DC voltage; and judging a generation of anerror of the operating lamps using the analog DC voltage to supply adisable signal to the master driver and the slave driver or to supplythe enable signal to the master driver and the slave driver inaccordance with the result. Herein, the present invention furtherincludes the steps of converting a master AC voltage fed back from themaster trans into a master DC voltage and converting a slave AC voltagefed back from the slave trans into a slave DC voltage; judging aninitial error generation of the lamps using the fed back master DCvoltage and the slave DC voltage at an initial driving condition togenerate an initial error signal and an initial normal signal inaccordance with the result; and stopping an initial drive of the masterdriver and the slave driver in response to the initial error signal.

The present invention, in a backlight driving apparatus of the LCDapparatus including a master trans and a slave trans for supplying acurrent to a plurality of lamps, and a master driver and a slave driverfor driving the lamps, comprises an operating condition detect means forconverting a AC voltage generated by a phase difference of a master ACvoltage and a slave AC voltage fed back from the master trans and theslave trans into an analog DC voltage; and a main control means forcontrolling an output of the master driver and the slave driver inresponse to the inputted burst dimming signal, and for judging an errorgeneration of the operating lamps using the analog DC voltage to stop adrive of the master driver and the slave driver or to normally drive themaster driver and the slave driver in accordance with the result.Herein, the present invention further includes a voltage feedback meansfor converting a master AC voltage fed back from the master trans into amaster DC voltage and for converting a slave AC voltage fed back fromthe slave trans into a slave DC voltage to output it to the main controlmeans.

The present invention, in a backlight driving apparatus of the LCDapparatus including a master trans and a slave trans for supplying acurrent to a plurality of lamps and a master driver and a slave driverfor driving the lamps, comprises a feedback portion for feeding back amaster AC voltage outputted from the master trans and a slave AC voltageoutputted from the slave trans; and a protective controller for judgingan error generation using a master AC voltage and a slave AC voltage fedback by the feedback portion to stop a drive of the master driver andthe slave driver upon generation of an error.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is an equivalent circuit diagram of a pixel of an LCD apparatusaccording to the related art;

FIG. 2 is a block diagram illustrating a configuration of an LCDapparatus according to the related art;

FIG. 3 is a block diagram illustrating a configuration of a backlightdriving apparatus of an LCD apparatus according to the related art;

FIG. 4 is a block diagram illustrating a configuration of a backlightdriving apparatus of an LCD apparatus according to an embodiment of thepresent invention;

FIG. 5 is a circuit diagram of the first and second master voltagesplitters shown in FIG. 4;

FIG. 6 is a circuit diagram of the first and second slave voltagesplitters shown in FIG. 4;

FIG. 7 is a circuit diagram of the operated condition detector shown inFIG. 4;

FIG. 8 is a circuit diagram of the master AC/DC converter shown in FIG.4;

FIG. 9 is a circuit diagram of the slave AC/DC converter shown in FIG.4;

FIG. 10 is a block diagram illustrating a configuration of a backlightdriving apparatus of an LCD apparatus according to another embodiment ofthe present invention;

FIG. 11 is a block diagram illustrating a configuration of a backlightdriving apparatus according to still another embodiment of the presentinvention;

FIG. 12 is a voltage waveform when an error is generated during theoperation of the backlight driving apparatus of an LCD apparatusaccording to still another embodiment of the present invention;

FIG. 13 is a block diagram illustrating a configuration of theprotective controller shown in FIG. 11;

FIG. 14 is a block diagram illustrating a configuration of a backlightdriving apparatus of a liquid crystal display apparatus according tostill another embodiment of the present invention; and

FIG. 15 is a block diagram illustrating a configuration of a backlightdriving apparatus of a liquid crystal display apparatus according to yetanother embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. The same reference numbers may be used throughout the drawingsto refer to the same or like parts.

FIG. 4 is a block diagram showing a configuration of a backlight drivingapparatus of a liquid crystal display (LCD) apparatus according to anembodiment of the present invention.

Referring to FIG. 4, the backlight driving apparatus 300 according tothe embodiment of the present invention includes a master DC/ACswitching portion 205, a slave DC/AC switching portion 206, a mastertrans 207 and a slave trans 208.

The backlight driving apparatus 300 further includes a lamp drivingcontroller 301 for generating a push-pull gate signal for controlling aplurality of lamps 201 in accordance with the burst dimming signal, amaster driver 302 and a slave driver 303 for generating pull-bridge gatesignals for driving the plurality of lamps 201 in response to thepush-pull gate signal, first and second master voltage splitters 304 and305 for lowering and feeding back a master AC voltage outputted from themaster trans 207, first and second slave voltage splitters 306 and 307for lowering and feeding back a slave AC voltage outputted from theslave trans 208, an operated condition detector 308 for converting an ACerror voltage generated on a basis of a phase difference between themaster AC voltage and the slave AC voltage fed back by the first mastervoltage splitter 304 and the first slave voltage splitter 306 into a DCerror voltage, a master AC/DC converter 309 for converting the master ACvoltage fed back by the second master voltage splitter 305 into a masterDC voltage, and a slave AC/DC converter 310 for converting the slave ACvoltage fed back by the second slave voltage splitter 307 into a slaveDC voltage, and a protective controller 311 for directly outputting anoperated error signal to the lamp driving controller 301 using a voltagefed back via the operated condition detector 308 to stop driving themaster driver 302 and the slave driver 303 when an error is generatedduring the operation and for directly outputting an initial error signalto the lamp driving controller 301 using a voltage fed back via themaster AC/DC converter 309 and/or the slave AC/DC converter 310 to stopdriving the master driver 302 and the slave driver 303 when an initialdriving error is generated.

The lamp driving controller 301 generates the push-pull gate signal forcontrolling the switching operations of the master AC/DC switchingportion 205 and the slave AC/DC switching portion 206 in accordance withthe burst dimming signal, and the push-pull gate signal is supplied tothe master driver 302 and the slave driver 303. When the initial errorsignal is generated from the protective controller 311 at an initialdriving condition, the lamp driving controller 301 outputs the disablesignal in response to the initial error signal to stop the drive of themaster driver 302 and the slave driver 303. Also, when the operatedcontrol signal is generated from the protective controller 311 at anoperating condition, the lamp driving controller 301 outputs the disablesignal in response to the operated error signal to stop the drive of themaster driver 302 and the slave driver 303. Herein, a lamp burst dimmingsignal is a signal for adjusting a brightness of the plurality of lamps201.

The master driver 302 generates the pull-bridge gate signal forcontrolling a switching of the master DC/AC switching portion 205 inresponse to the push-pull gate signal inputted from the lamp drivingcontroller 301 to output it to the master DC/AC switching portion 205.When the disable signal is inputted to the master driver 302 from thelamp driving controller 301 at a driving condition or at an operatingcondition, then the master driver 302 stops generating the pull-bridgegate signal.

The slave driver 303 generates the pull-bridge gate signal forcontrolling a switching of the slave DC/AC switching portion 206 inresponse to the push-pull gate signal inputted from the lamp drivingcontroller 301 to output it to the slave DC/AC switching portion 206.When the disable signal is inputted to the slave driver 303 from thelamp driving controller 301 at a driving condition or at an operatingcondition, then the slave driver 303 stops generating the pull-bridgegate signal.

The first master voltage splitter 304 drops a master AC voltage of 1.2KV to 1.3 KV outputted from the master trans 207 into 12V to 13V andfeeds it back to the operated condition detector 308. The second mastervoltage splitter 305 drops a master AC voltage of 1.2 KV to 1.3 KVoutputted from the master trans 207 into 12V to 13V and feeds it back tothe master AC/DC converter 309.

The first slave voltage splitter 306 drops a slave AC voltage of 1.2 KVto 1.3 KV outputted from the slave trans 208 into 12V to 13V and feedsit back to the operated condition detector 308. The second slave voltagesplitter 307 drops a master AC voltage of 1.2 KV to 1.3 KV outputtedfrom the slave trans 208 into 12V to 13V and feeds it back to the slaveAC/DC converter 310.

The operated condition detector 308 converts an AC error voltagegenerated on a basis of a phase difference between the master AC voltageand the slave AC voltage fed back by the first master voltage splitter304 and the first slave voltage splitter 306 into a DC error voltage andoutputs it to the protective controller 311. When there is no phasedifference between the master AC voltage and the slave AC voltage, theoperated condition detector 308 outputs substantially 0V to theprotective controller 311.

The master AC/DC converter 309 converts the master AC voltage fed backby the second master voltage splitter 305 into a master DC voltage andoutputs it to the protective controller 311.

The slave AC/DC converter 310 converts the slave AC voltage fed back bythe second slave voltage splitter 307 into a slave DC voltage andoutputs it to the protective controller 311.

The protective controller 311 converts the analog DC voltage fed back bythe master AC/DC converter 309 and the slave AC/DC converter 310 intofirst and second digital feedback voltages, and compares the magnitudeof the first and second digital feedback voltages with the referenceinitial voltage to judge whether there is an error at the initialdriving condition. When the magnitude of the digital feedback voltagesis the same as the reference initial voltage, the protective controller311 determines that the initial driving condition is normal and outputsan enable signal to the lamp driving controller 301. When the magnitudesare different from each other, then the protective controller 311determines that there is an error at the initial driving condition andoutputs the initial error signal to the lamp driving controller 301.

The protective controller 311 also converts the analog DC voltage fedback by the operated condition detector 308 into the digital feedbackvoltage, and compares the magnitude of the digital feedback voltage withthe reference operating voltage to determine whether there is an errorat the operating condition. When the magnitude of the digital feedbackvoltage is the same as the reference initial voltage, the protectivecontroller 311 determines that the operating condition is normal andoutputs the enable signal to the lamp driving controller 301. When themagnitudes are different from each other, then the protective controller311 determines that there is an error at the operating condition andoutputs the operated error signal to the lamp driving controller 301.Herein, when the operating condition is normal, then because the phasesof a master AC voltage and a slave AC voltage fed back by the firstmaster voltage splitter 304 and the first slave voltage splitter 306 arethe same, the operated condition detector 308 substantially outputs avoltage of 0V to the protective controller 311. On the other hand, whenan error is generated during an operation, then because a phasedifference between a master AC voltage and a slave AC voltage fed backby the first master voltage splitter 304 and the first slave voltagesplitter 306 is generated, the operated condition detector 308 convertsan AC error voltage among an operations generated by a phase differencebetween the fed back master AC voltage and the slave AC voltage into aDC error voltage to output it to the protective controller 311. In otherwords, the protective controller 311 converts an analog DC error voltageconverted by the operated condition detector 308 into a digital errorvoltage, and compares the reference operating voltage with the digitalerror voltage to judge whether there is an error.

As described above, when an error is generated during the operation ofthe backlight driving apparatus according to the present invention, theprotective controller 311 detects the generation of an error using afeed back voltage, and then outputs an operated error signal to the lampdriving controller 301. The lamp driving controller 301 then outputs thedisable signal in response to the operated error signal to stop drivingthe master driver 302 and the slave driver 303.

The backlight driving apparatus according to the present inventiondetects an error during the operation and the protective controller 311then stops driving the master driver 302 and the slave driver 303.Accordingly, a damage to an inspector such as an electric shock can beminimized or prevented.

FIG. 5 is a circuit diagram of the first and second master voltagesplitters shown in FIG. 4.

Referring to FIG. 5, the first master voltage splitter 304 includescapacitors C1 and C2 serially connected between an output the mastertrans 207 and the ground. A voltage allotted by the capacitors C1 and C2is transmitted to the operated condition detector 308 via a nodepositioned between the capacitors C1 and C2.

The second master voltage splitter 305 includes capacitors C3 and C4serially connected between an output the master trans 207 and theground. The capacitors C3 and C4 are connected to the capacitors C1 andC2 in parallel. A voltage allotted by the capacitors C3 and C4 istransmitted to the master AC/DC converter 309 via a node positionedbetween the capacitors C3 and C4.

FIG. 6 is a circuit diagram of the first and second slave voltagesplitters shown in FIG. 4.

Referring to FIG. 6, the first slave voltage splitter 306 includescapacitors C5 and C6 serially connected between an output the slavetrans 208 and the ground. A voltage allotted by the capacitors C5 and C6is transmitted to the operated condition detector 308 via a nodepositioned between the capacitors C5 and C6.

The second slave voltage splitter 307 includes capacitors C7 and C8serially connected between an output the slave trans 208 and the ground.The capacitors C7 and C8 are connected to the capacitors C5 and C6 inparallel. A voltage allotted by the capacitors C7 and C8 is transmittedto the slave AC/DC converter 310 via a node positioned between thecapacitors C7 and C8.

FIG. 7 is a circuit diagram of an operated condition detector shown inFIG. 4.

Referring to FIG. 7, the operated condition detector 308 includes aresistance R1 connected to an output the first master voltage splitter304, a resistance R2 connected to an output the first slave voltagesplitter 306, a resistance R3 connected between the resistances R1 andR2 and the ground, a resistance connected between the protectivecontroller 311 and the resistance R1, a resistance R5 connected betweenthe protective controller 311 and the resistance R4 and the ground. Theoperated condition detector 308 further includes a capacitor C9connected between the resistances R1 and R4 and the ground, and acapacitor C10 connected between the protective controller 311 and theresistance R4 and the ground. The capacitor C9 is connected to theresistance R3 in parallel and C10 is connected to the resistance R5 inparallel.

FIG. 8 is a circuit diagram of the master AC/DC converter shown in FIG.4.

Referring to FIG. 8, the master AC/DC converter 309 includes a diode D1in which an anode is connected to an output the second master voltagesplitter 305 and a cathode is connected to the protective controller311, a diode D2 in which an anode is connected to the ground and acathode is connected to the cathode of the diode D1, a resistance R6connected between the cathode of the diode D1 and the protectivecontroller 311 and the ground, and a capacitor C11 connected between thecathode of the diode D1 and the protective controller 311 and theground. C11 is also connected to the resistance R6 in parallel. Also,the cathode of the diode D2 is connected to the diode D1 and R6 isconnected to the diode D2 in parallel.

FIG. 9 is a circuit diagram of the slave AC/DC converter shown in FIG.4.

Referring to FIG. 9, the slave AC/DC converter 310 includes a diode D3in which an anode is connected to an output the second slave voltagesplitter 307 and a cathode is connected to the protective controller311, a diode D4 in which an anode is connected to the ground and acathode is connected to the cathode of the diode D3, a resistance R7connected between the cathode of the diode D3 and the protectivecontroller 311 and the ground, and a capacitor C12 connected between thecathode of the diode D3 and the protective controller 311 and theground. C12 is also connected to the resistance R7 in parallel. Also,the cathode of the diode D4 is connected to the diode D3 and R7 isconnected to the diode D4 in parallel.

FIG. 10 is a block diagram illustrating a configuration of a backlightdriving apparatus of an LCD apparatus according to another embodiment ofthe present invention.

Referring to FIG. 10, a backlight driving apparatus 300 similar to thebacklight driving apparatus 300 illustrated in FIG. 4 includes a masterAC/DC switching portion 205, a slave AC/DC switching portion 206, amaster trans 207, a slave trans 208, a master driver 302, a slave driver303, first and second master voltage splitters 304 and 305, first andsecond slave voltage splitters 306 and 307, an operated conditiondetector 308, a master AC/DC converter 309 and a slave AC/DC converter310.

The backlight driving apparatus 400 also includes a main controller 410for generating a push-pull gate signal for controlling the plurality oflamps 201 in accordance with the burst dimming signal and for generatingan operated error signal that judges an error during an operation usinga voltage fed back via the operated condition detector 308 to indicate adrive stop of the master driver 302 and the slave driver 303 when anerror is generated, and for generating an initial error signal thatjudges an error of an initial drive using a voltage fed back via themaster AC/DC converter 309 and/or the slave AC/DC converter 310 toindicate a drive stop of the master driver 302 and the slave driver 303when an error is generated.

The lamp driving controller 301 and the protective controller 311illustrated in FIG. 4 are implemented in the main controller 410 of asingle chip, and a function thereof is as follows.

The main controller 410 generates a push-pull gate signal forcontrolling an switching operations of the master DC/AC switchingportions 205 and the slave DC/AC switching portions in accordance withthe lamp burst dimming signal to supply them to the master driver 302and the slave driver 303.

The main controller 410 converts the analog DC voltage fed back by themaster AC/DC converter 309 and the slave AC/DC converter 310 into firstand second digital feedback voltages, and compares the magnitude of thefirst and second digital feedback voltages with the reference initialvoltage to judge whether there is an error at the initial drivingcondition. When the magnitude of the digital feedback voltages is thesame as the reference initial voltage, the main controller 410 judgesthe initial driving condition as a normal to output the enable signal.When the magnitudes are different from each other, then the maincontroller 410 judges a generation of an error at the initial drivingcondition to output the initial error signal.

The main controller 410 converts the analog DC voltage fed back by theoperated condition detector 308 into the digital feedback voltage, andcompares the magnitude of the digital feedback voltage with thereference operating voltage to judge whether there is an error at theoperating condition. When the magnitude of the digital feedback voltageis the same as the reference initial voltage, the main controller 410judges the operating condition as a normal to output the enable signal.When the magnitudes are different from each other, then the maincontroller 410 judges a generation of an error at the operatingcondition to output the operated error signal. In other words, the maincontroller 410 converts an analog DC error voltage converted by theoperated condition detector 308 into the digital error voltage, andcompares the reference operating voltage with the digital error voltageto judge whether there is an error during an operation.

If an initial error signal is generated at an initial driving condition,then the main controller 410 outputs the disable signal in response toan initial error signal to stop driving the master driver 302 and theslave driver 303. Also, if an operated error signal is generated at anoperating condition, then the main controller 410 outputs the disablesignal in response to an operated error signal to stop driving themaster driver 302 and the slave driver 303.

As described above, in the backlight driving apparatus 400 according toanother embodiment of the present invention, if an error is generatedduring an operation, then the main controller 410 detects the generationof an error during an operation using a feedback voltage and thenoutputs the disable signal to stop driving the master driver 302 and theslave driver 303.

FIG. 11 is a block diagram illustrating a configuration of a backlightdriving apparatus according to still another embodiment of the presentinvention.

Referring to FIG. 11, the backlight driving apparatus 500 similar to thebacklight driving apparatus 300 illustrated in FIG. 4 includes a masterAC/DC switching portion 205, a slave AC/DC switching portion 206, amaster trans 207, a slave trans 208, a master driver 302, a slave driver303, first and second master voltage splitters 304 and 305, first andsecond slave voltage splitters 306 and 307, an operated conditiondetector 308, a master AC/DC converter 309 and a slave AC/DC converter310.

The backlight driving apparatus 500 also includes a lamp drivingcontroller 510 for generating a push-pull gate signal for controllingthe plurality of lamps 201 in accordance with the burst dimming signaland a protective controller 520 for directly outputting an operatederror signal that judges an error during an operation using a voltagefed back via the operated condition detector 308 to indicate a drivestop of the master driver 302 and the slave driver 303 when an error isgenerated, and for outputting an initial error signal that judges anerror of an initial drive using a voltage fed back via the master AC/DCconverter 309 and the slave AC/DC converter 310 to indicate a drive stopof the master driver 302 and the slave driver 303 when an error isgenerated to the lamp driving controller 510.

The lamp driving controller 510 generates the push-pull gate signal forcontrolling the switching operations of the master AC/DC switchingportion 205 and the slave AC/DC switching portion 206 in accordance withthe burst dimming signal, and the push-pull gate signal is supplied tothe master driver 302 and the slave driver 303. When the initial errorsignal is generated from the protective controller 520 at an initialdriving condition, the lamp driving controller 510 outputs the disablesignal in response to the initial error signal to stop the drive of themaster driver 302 and the slave driver 303.

An analog master DC voltage fed back via the master AC/DC converter 309and an analog slave DC voltage fed back via the slave AC/DC converter310 are inputted to the protective controller 520 at an initial drivingcondition, then the protective controller 520 converts the fed backanalog master DC voltage into a first digital feedback voltage andconverts the fed back analog slave DC voltage into a second digitalfeedback voltage, and compares the magnitude of the first and seconddigital feedback voltages with the reference initial voltage to judgewhether there is an error at the initial operation. When the magnitudeof the digital feedback voltages is the same as the reference initialvoltage, the protective controller 520 judges the initial operation as anormal to control the lamp driving controller 510 in such a manner toallow the lamps 201 to be continuously driven. When the magnitudes aredifferent from each other, then the protective controller 520 judges ageneration of an error at the initial operation to output the initialerror signal to the lamp driving controller 510. If the initial errorsignal is generated, then the lamp driving controller 510 outputs thedisable signal to the master driver 302 and the slave driver 303 inresponse to the initial error signal to stop an operation of the masterdriver 302 and the slave driver 303.

An analog master DC voltage fed back via the operated condition detector308 is inputted to the protective controller 520 at an operatingcondition, then the protective controller 520 compares the magnitude ofthe feedback voltage with the reference initial voltage to output theenable signal or the disable signal to the master driver 302 and theslave driver 303 in accordance with the result. When the magnitude ofthe feedback voltage is the same as the reference initial voltage, theprotective controller 520 generates the enable signal to output it tothe master driver 302 and the slave driver 303. When the magnitudes aredifferent from each other, then the protective controller 520 generatesthe disable signal to output it to the master driver 302 and the slavedriver 303. If the disable signal is inputted from the protectivecontroller 520, then the operations of the master driver 302 and theslave driver 303 are stopped by the disable signal.

The master driver 302 generates the pull-bridge gate signal forcontrolling a switching of the master DC/AC switching portion 205 inresponse to the push-pull gate signal inputted from the lamp drivingcontroller 510 to output it to the master DC/AC switching portion 205.When the disable signal is inputted to the master driver 302 from thelamp driving controller 510 at initial driving condition, then themaster driver 302 stops generating the pull-bridge gate signal. When thedisable signal is inputted to the master driver 302 from the protectivecontroller 520 at operating condition, then the master driver 302 stopsgenerating the pull-bridge gate signal. On the other hand, when theenable signal is inputted to the master driver 302 from the protectivecontroller 520 at operating condition, then the master driver 302generates the pull-bridge gate signal in response to the push-pull gatesignal inputted from the lamp driving controller 510.

The slave driver 303 generates the pull-bridge gate signal forcontrolling a switching of the slave DC/AC switching portion 206 inresponse to the push-pull gate signal inputted from the lamp drivingcontroller 510 to output it to the slave DC/AC switching portion 206.When the disable signal is inputted to the slave driver 303 from thelamp driving controller 510 at initial driving condition, then the slavedriver 303 stops generating the pull-bridge gate signal. And when thedisable signal is inputted to the slave driver 303 from the protectivecontroller 520 at operating condition, then the slave driver 303 stopsgenerating the pull-bridge gate signal. On the other hand, when theenable signal is inputted to the slave driver 303 from the protectivecontroller 520 at operating condition, then the slave driver 303generates the pull-bridge gate signal in response to the push-pull gatesignal inputted from the lamp driving controller 510.

As described above, if an error is generated during an operation of thebacklight driving apparatus 500, then the protective controller 520directly outputs the disable signal to the master driver 302 and theslave driver 303 to stop a drive thereof, so that the backlight drivingapparatus 500 spends a time of approximately 10 μs from an errorgeneration point during an operation to a drive stop point of the masterdriver 302 and the slave driver 303. Accordingly, the backlight drivingapparatus 500 substantially reduces the duration of a high voltage thatmay inflict a damage to an inspector such as an electric shock, etc., asillustrated in FIG. 12.

The lamp driving controller 510 and the protective controller 520 may beimplemented in a single chip.

FIG. 13 a block diagram illustrating a configuration of the protectivecontroller shown in FIG. 11.

Referring to FIG. 13, the protective controller 520 includes an A/Dconverter 521 for converting an analog DC voltage fed back via themaster AC/DC converter 309 and the slave AC/DC converter 310 into thefirst and second digital feedback voltages at the initial drivingcondition, an error sensor 522 for comparing a magnitude of the firstand second digital feedback voltages with the reference initial voltageto output an initial normal signal that shows a normal of the initialerror signal or an initial operation to the lamp driving controller 510in accordance with the result, and a comparator 523 for comparing amagnitude of an analog DC voltage fed back via the operated conditiondetector 308 with the reference operating voltage at an operatingcondition to output the enable signal or the disable signal to themaster driver 302 and the slave driver 303 in accordance with theresult.

If an analog master DC voltage fed back via the master AC/DC converter309 and an analog slave DC voltage fed back via the slave AC/DCconverter 310 are inputted to the A/D converter 521 at the initialdriving condition, then the A/D converter 521 converts the fed backanalog master DC voltage into a first digital feedback voltage andconverts the fed back analog slave DC voltage into a second digitalfeedback voltage to output them to the error sensor 522. Herein, the A/Dconverter 521 sequentially outputs first and second digital feedbackvoltage, and the output order is set in a hardware system method. Forexample, the A/D converter 521 primarily outputs a first digitalfeedback voltage inputted to one input terminal of two input terminals,and then outputs a second digital feedback voltage inputted to anotherinput terminal.

The error sensor 522 compares a magnitude of a first and second digitalfeedback voltage converted by the A/D converter 521 with the referenceinitial voltage to judge an error generation of an initial operation.When the magnitude of a first and second digital feedback voltage is thesame as the reference initial voltage, the error sensor 522 judges aninitial operation as a normal to output an initial normal signal to thelamp driving controller 510. When the magnitudes are different from eachother, the error sensor 522 judges an error generation of the initialoperation to output the initial error signal to the lamp drivingcontroller 510.

The comparator 523 is inputted with the reference operating voltagethrough a non-inverted input terminal (+) and a voltage fed back throughan inverted input terminal (−) to output the disable signal and theenable signal to the master driver 302 and the slave driver 303connected to an output terminal.

If an analog DC voltage fed back via the operated condition detector 308is inputted to the non-inverted input terminal (+) and the referenceoperating voltage is inputted to the inverted input terminal (−) at theoperating condition, then the comparator 523 compares a magnitude of thefeedback voltage with the reference operating voltage to output theenable signal to the disable signal to the master driver 302 and theslave driver 303 in accordance with the result. When the magnitudes arethe same, the comparator 523 generates the enable signal to output it tothe master driver 302 and the slave driver 303. When the magnitudes aredifferent from each other, the comparator 523 generates the disablesignal to output the master driver 302 and the slave driver 303.

As described above, the present invention automatically shields avoltage supply upon the generation of an error during an operation oflamps of the liquid crystal display apparatus, so that it becomespossible to minimize or prevent a damage caused by an error to aninspector.

Also, the present invention substantially reduces a time interval untila shielding point of a voltage supply upon a generation of an erroramong the operations of lamps of the liquid crystal display apparatus,so that it becomes possible to minimize or prevent a high voltage frominflicting a damage such as an electric shock, etc to an inspector.

FIG. 14 is a block diagram illustrating a configuration of a backlightdriving apparatus of a liquid crystal display apparatus according tostill another embodiment of the present invention.

Referring to FIG. 14, the backlight driving apparatus 600 similar to thebacklight driving apparatus 500 illustrated in FIG. 11 includes a masterdriver 302, a slave driver 303, a master AC/DC switching portion 205, aslave AC/DC switching portion 206, a master trans 207, a slave trans208.

The backlight driving apparatus 600 includes a lamp driving controller610 for controlling the master driver 302 and the slave driver 303 inaccordance with the inputted burst dimming signal, a feedback portion620 for feeding back a master AC voltage outputted from the master trans207 and a slave AC voltage outputted from the slave trans 208, and aprotective controller 630 for detecting the generation of an error usinga master AC voltage and a slave AC voltage fed back by the feedbackportion 620 to stop driving the master driver 302 and the slave driver303 upon generation of an error.

The feedback portion 620 feeds back an output voltage of the masterdriver 302 and the slave driver 303, and a feedback method may bediversely implemented. Also, a method of driving the protectivecontroller 630 is diversified in accordance with a feedback method ofthe feedback portion 620.

First, a case where the feedback portion 620 is implemented by a firstfeedback method will be described.

The feedback portion 620 drops and feeds back a master AC voltageoutputted from the master trans 207, and drops and feeds back a slave ACvoltage outputted from the slave trans 208 at the initial condition.Herein, the feedback portion 620 converts a feedback master AC voltageinto a feedback master DC voltage and converts a feedback slave ACvoltage into a feedback slave DC voltage to feed back them to theprotective controller 630. Specially, the feedback portion 620sequentially outputs a feedback master DC voltage and a feedback slaveDC voltage to the protective controller 630 at the initial condition.

The feedback portion 620 drops a master AC voltage fed back from themaster trans 207 and drops a slave AC voltage fed back from the slavetrans 208 at the operating condition, and then converts an analog ACvoltage generated by a phase difference between the fed back master ACvoltage and the slave AC voltage into an analog DC voltage to output itto the protective controller 630. Herein, when there is no phasedifference between the fed back master AC voltage and the slave ACvoltage, the feedback portion 620 outputs substantially 0V to theprotective controller 630 because the fed back master AC voltage and theslave AC voltage have an inverse phase relation.

The protective controller 630 converts an analog DC voltage fed back viathe feed back portion 620 into a digital feedback voltage at the initialcondition, and compares the magnitude of the reference initial voltagewith a digital feedback voltage to judge whether there is an error atthe initial driving condition. When the magnitude of the referenceinitial voltage is the same as a digital feedback voltage, theprotective controller 630 judges the initial driving condition as anormal to output an enable signal to the master driver 302 and the slavedriver 303. When the magnitudes are different from each other, then theprotective controller 630 judges a generation of an error at the initialcondition to output a disable signal to the master driver 302 and theslave driver 303.

The protective controller 630 converts an analog DC voltage fed back viathe feed back portion 620 into a digital AC voltage at the operatingcondition, and compares the magnitude of the reference initial voltagewith a digital AC voltage to judge whether there is an error at theoperating condition. When the magnitude of the reference initial voltageis the same as a digital AC voltage, the protective controller 630judges the operating condition as a normal to output an enable signal tothe master driver 302 and the slave driver 303. When the magnitudes aredifferent from each other, then the protective controller 630 judges ageneration of an error at the operating condition to output a disablesignal to the master driver 302 and the slave driver 303.

Next, a case where the feedback portion 620 is implemented by a secondfeed back method will be described.

The feedback portion 620 drops and feeds back a master AC voltageoutputted from the master trans 207, and drops and feeds back a slave ACvoltage outputted from the slave trans 208 at the operating condition.Herein, the feedback portion 620 converts a feedback master AC voltageinto a feedback master DC voltage and converts a feedback slave ACvoltage into a feedback slave DC voltage to feed back them to theprotective controller 630. Specially, the feedback portion 620sequentially outputs a feedback master DC voltage and a feedback slaveDC voltage to the protective controller 630 at the operating condition.

And, the feedback portion 620 drops a master AC voltage fed back fromthe master trans 207 and drops a slave AC voltage fed back from theslave trans 208 at the initial condition, and then converts an analog ACvoltage generated by a phase difference between the fed back master ACvoltage and the slave AC voltage into an analog DC voltage to output itto the protective controller 630. Herein, when there is no phasedifference between the fed back master AC voltage and the slave ACvoltage, the feedback portion 620 outputs substantially 0V to theprotective controller 630 because the fed back master AC voltage and theslave AC voltage have an inverse phase relation.

The protective controller 630 converts an analog DC voltage fed back viathe feed back portion 620 into a digital feedback voltage at theoperating condition, and compares the magnitude of the referenceoperating voltage with a digital feedback voltage to judge whether thereis an error at the operating condition. When the magnitude of thereference operating voltage is the same as a digital feedback voltage,the protective controller 630 judges the operating condition as a normalto output an enable signal to the master driver 302 and the slave driver303. When the magnitudes are different from each other, then theprotective controller 630 judges a generation of an error at theoperating condition to output a disable signal to the master driver 302and the slave driver 303.

The protective controller 630 converts an analog DC voltage fed back viathe feed back portion 620 into a digital AC voltage at the initialcondition, and compares the magnitude of the reference initial voltagewith a digital AC voltage to judge whether there is an error at theinitial condition. When the magnitude of the reference initial voltageis the same as a digital AC voltage, the protective controller 630judges the initial condition as a normal to output an enable signal tothe master driver 302 and the slave driver 303. When the magnitudes aredifferent from each other, then the protective controller 630 judges ageneration of an error at the initial condition to output a disablesignal to the master driver 302 and the slave driver 303.

On the other hand, the protective controller 630 may be implemented insuch a manner to compare a magnitude an analog DC voltage and thereference voltage fed back via the feedback portion 620 to thereby judgewhether there is an error at the initial condition or at the operatingcondition. In this case, the protective controller 630 does not carryout a process in which the fed back analog DC voltage is converted intoa digital voltage.

FIG. 15 is a block diagram illustrating a configuration of a backlightdriving apparatus of a liquid crystal display apparatus according to yetanother embodiment of the present invention.

Referring to FIG. 15, the backlight driving apparatus 700 similar to thebacklight driving apparatus 500 illustrated in FIG. 11 includes a masterdriver 302, a slave driver 303, a master AC/DC switching portion 205, aslave AC/DC switching portion 206, a master trans 207, and a slave trans208.

The backlight driving apparatus 700 also includes a lamp drivingcontroller 710 for controlling the master driver 302 and the slavedriver 303 in accordance with the inputted burst dimming signal, afeedback portion 720 for feeding back a master AC voltage outputted fromthe master trans 207 and a slave AC voltage outputted from the slavetrans 208, and a protective controller 730 for judging an errorgeneration using a master AC voltage and a slave AC voltage fed back bythe feedback portion 720 to stop driving the master driver 302 and theslave driver 303 upon generation of an error.

The feedback portion 720 feeds back an output voltage of the masterdriver 302 and the slave driver 303, and a feedback method may bediversely implemented. Also, a method of driving the protectivecontroller 730 is diversified in accordance with a feedback method ofthe feedback portion 720.

First, a case where the feedback portion 720 is implemented by a thirdfeedback method will be described.

The feedback portion 720 drops and feeds back a master AC voltageoutputted from the master trans 207, and drops and feeds back a slave ACvoltage outputted from the slave trans 208 at the initial condition orat the operating condition. Herein, the feedback portion 720 converts afeedback master AC voltage into a feedback master DC voltage andconverts a feedback slave AC voltage into a feedback slave DC voltage tofeed back them to the protective controller 730. Specially, the feedbackportion 720 sequentially outputs a feedback master DC voltage and afeedback slave DC voltage to the protective controller 730.

The protective controller 730 converts an analog DC voltage fed back viathe feed back portion 720 into a digital feedback voltage at the initialcondition or at the operating condition, and compares the magnitude ofthe reference voltage with a digital feedback voltage to judge whetherthere is an error at the initial condition or at the operatingcondition. When the magnitude of the reference voltage is the same as adigital feedback voltage, the protective controller 730 judges theinitial condition or the operating condition as a normal to output anenable signal to the master driver 302 and the slave driver 303. Whenthe magnitudes are different from each other, then the protectivecontroller 730 judges a generation of an error at the initial conditionor at the operating condition to output a disable signal to the masterdriver 302 and the slave driver 303.

Next, a case where the feedback portion 720 is implemented by a fourthfeed back method will be described.

The feedback portion 720 drops a master AC voltage fed back from themaster trans 207 and drops a slave AC voltage fed back from the slavetrans 208 at the initial condition or at the operating condition, andthen converts an analog AC voltage generated by a phase differencebetween the fed back master AC voltage and the slave AC voltage into ananalog DC voltage to output it to the protective controller 730. Herein,when there is no phase difference between the fed back master AC voltageand the slave AC voltage, the feedback portion 720 outputs substantially0V to the protective controller 730 because the fed back master ACvoltage and the slave AC voltage have an inverse phase relation.

The protective controller 730 converts an analog DC voltage fed back viathe feed back portion 720 into a digital AC voltage at the initialcondition or at the operating condition, and compares the magnitude ofthe reference voltage with a digital AC voltage to judge whether thereis an error at the initial condition or at the operating condition. Whenthe magnitude of the reference voltage is the same as a digital feedbackvoltage, the protective controller 730 judges the initial condition orthe operating condition as a normal to output an enable signal to themaster driver 302 and the slave driver 303. When the magnitudes aredifferent from each other, then the protective controller 730 judges ageneration of an error at the initial condition or at the operatingcondition to output a disable signal to the master driver 302 and theslave driver 303.

The protective controller 730 may be implemented in such a manner tocompare a magnitude an analog DC voltage and the reference voltage fedback via the feedback portion 720 to thereby judge whether there is anerror at the initial condition or at the operating condition. In thiscase, the protective controller 730 does not carry out a process inwhich the fed back analog DC voltage is converted into a digitalvoltage.

As described above, the present invention detects an initial drivingerror using the fed back master AC voltage and the slave AC voltage.According to the principles of the present invention, any one of the fedback master AC voltage and the slave AC voltage may be used to detect aninitial driving error.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A backlight driving apparatus of a liquid crystal display LCDapparatus including a master trans and a slave trans for supplying acurrent to a plurality of lamps, and a master driver and a slave driverfor driving the lamps, comprising: a feedback portion for feeding back amaster AC voltage outputted from the master trans and a slave AC voltageoutputted from the slave trans; and a protective controller for judgingan error generation using a master AC voltage and a slave AC voltage fedback by the feedback portion to stop a drive of the master driver andthe slave driver upon generation of an error.
 2. The backlight drivingapparatus as claimed in claim 1, wherein said feedback portion convertsa master AC voltage fed back from the master trans into a feedbackmaster DC voltage and converts a slave AC voltage fed back from theslave trans into a feedback slave DC voltage at an initial condition,and sequentially outputs the feedback master DC voltage and the feedbackslave AC voltage to the protective controller.
 3. The backlight drivingapparatus as claimed in claim 2, wherein said protective controllerconverts the fed back master DC voltage and the fed back slave DCvoltage into a digital feedback voltage at an initial condition, andcompares the magnitude of the reference initial voltage with a digitalfeedback voltage to determine whether there is an error at an initialdriving condition.
 4. The backlight driving apparatus as claimed inclaim 3, wherein when the magnitude of the reference initial voltage isthe same as a digital feedback voltage, the protective controlleroutputs an enable signal to the master driver and the slave driver. 5.The backlight driving apparatus as claimed in claim 3, wherein when themagnitudes are different from each other, then the protective controlleroutputs a disable signal to the master driver and the slave driver. 6.The backlight driving apparatus as claimed in claim 2, wherein saidfeedback portion converts an analog AC voltage generated by a phasedifference between a master AC voltage and a slave AC voltage fed backfrom the master trans and the slave trans into an analog DC voltage tooutput it to the protective controller at an operating condition.
 7. Thebacklight driving apparatus as claimed in claim 6, wherein saidprotective controller converts an analog DC voltage fed back via thefeedback portion into a digital AC voltage at an operating condition,and compares the magnitude of the reference operating voltage with adigital AC voltage to determine whether there is an error at anoperating condition.
 8. The backlight driving apparatus as claimed inclaim 7, wherein when the magnitude of the reference operating voltageis the same as a digital AC voltage, the protective controller outputsan enable signal to the master driver and the slave driver.
 9. Thebacklight driving apparatus as claimed in claim 7, wherein when themagnitudes are different from each other, then the protective controlleroutputs a disable signal to the master driver and the slave driver. 10.The backlight driving apparatus as claimed in claim 2, wherein saidprotective controller compares the magnitude of an analog DC voltage fedback via the feedback portion with the reference operating voltage at anoperating condition to determine whether there is an error at anoperating condition.
 11. The backlight driving apparatus as claimed inclaim 10, wherein when the magnitude of the reference operating voltageis the same as the fed back analog DC voltage, the protective controlleroutputs an enable signal to the master driver and the slave driver. 12.The backlight driving apparatus as claimed in claim 10, wherein when themagnitudes are different from each other, then the protective controlleroutputs a disable signal to the master driver and the slave driver. 13.The backlight driving apparatus as claimed in claim 1, wherein saidfeedback portion converts a master AC voltage fed back from the mastertrans into a feedback master DC voltage and converts a slave AC voltagefed back from the slave trans into a feedback slave DC voltage at anoperating condition, and sequentially outputs the feedback master DCvoltage and the feedback slave AC voltage to the protective controller.14. The backlight driving apparatus as claimed in claim 13, wherein saidprotective controller converts the fed back master DC voltage and thefed back slave DC voltage into a digital feedback voltage at anoperating condition, and compares the magnitude of the referenceoperating voltage with a digital feedback voltage to determine whetherthere is an error at an operating condition.
 15. The backlight drivingapparatus as claimed in claim 14, wherein when the magnitude of thereference operating voltage is the same as a digital feedback voltage,the protective controller outputs an enable signal to the master driverand the slave driver.
 16. The backlight driving apparatus as claimed inclaim 14, wherein when the magnitudes are different from each other,then the protective controller outputs a disable signal to the masterdriver and the slave driver.
 17. The backlight driving apparatus asclaimed in claim 13, wherein said feedback portion an analog AC voltagegenerated by a phase difference between a master AC voltage and a slaveAC voltage fed back from the master trans and the slave trans into ananalog DC voltage to output it to the protective controller at aninitial condition.
 18. The backlight driving apparatus as claimed inclaim 17, wherein said protective controller converts an analog DCvoltage fed back via the feedback portion into a digital AC voltage atan initial condition, and compares the magnitude of the referenceinitial voltage with a digital AC voltage to determine whether there isan error at an initial condition.
 19. The backlight driving apparatus asclaimed in claim 18, wherein when the magnitude of the reference initialvoltage is the same as a digital AC voltage, the protective controlleroutputs an enable signal to the master driver and the slave driver. 20.The backlight driving apparatus as claimed in claim 18, wherein when themagnitudes are different from each other, then the protective controlleroutputs a disable signal to the master driver and the slave driver. 21.The backlight driving apparatus as claimed in claim 13, wherein saidprotective controller compares the magnitude of an analog DC voltage fedback via the feedback portion with the reference initial voltage at aninitial condition to determine whether there is an error at an initialcondition.
 22. The backlight driving apparatus as claimed in claim 21,wherein when the magnitude of the reference initial voltage is the sameas the fed back analog DC voltage, the protective controller outputs anenable signal to the master driver and the slave driver.
 23. Thebacklight driving apparatus as claimed in claim 21, wherein when themagnitudes are different from each other, then the protective controlleroutputs a disable signal to the master driver and the slave driver. 24.The backlight driving apparatus as claimed in claim 1, wherein saidfeedback portion converts a master AC voltage fed back from the mastertrans into a feedback master DC voltage and converts a slave AC voltagefed back from the slave trans into a feedback slave DC voltage at aninitial condition or an operating condition, and sequentially outputsthe feedback master DC voltage and the feedback slave AC voltage to theprotective controller.
 25. The backlight driving apparatus as claimed inclaim 24, wherein said protective controller converts the fed backmaster DC voltage and the fed back slave DC voltage into a digitalfeedback voltage at an initial condition or at an operating condition,and compares the magnitude of the reference voltage with a digitalfeedback voltage to determine whether there is an error at an initialcondition or at an operating condition.
 26. The backlight drivingapparatus as claimed in claim 25, wherein when the magnitude of thereference voltage is the same as a digital feedback voltage, theprotective controller outputs an enable signal to the master driver andthe slave driver.
 27. The backlight driving apparatus as claimed inclaim 25, wherein when the magnitudes are different from each other,then the protective controller outputs a disable signal to the masterdriver and the slave driver.
 28. The backlight driving apparatus asclaimed in claim 1, wherein said feedback portion converts an analog ACvoltage generated by a phase difference between a master AC voltage anda slave AC voltage fed back from the master trans and the slave transinto an analog DC voltage to output it to the protective controller atan initial condition or at an operating condition.
 29. The backlightdriving apparatus as claimed in claim 28, wherein said protectivecontroller converts an analog DC voltage fed back via the feedbackportion into a digital AC voltage at an initial condition or at anoperating condition, and compares the magnitude of the reference voltagewith a digital AC voltage to determine whether there is an error at aninitial condition or at an operating condition.
 30. The backlightdriving apparatus as claimed in claim 29, wherein when the magnitude ofthe reference voltage is the same as a digital AC voltage, theprotective controller outputs an enable signal to the master driver andthe slave driver.
 31. The backlight driving apparatus as claimed inclaim 29, wherein when the magnitudes are different from each other,then the protective controller outputs a disable signal to the masterdriver and the slave driver.
 32. The backlight driving apparatus asclaimed in claim 1, wherein said feedback portion outputs an analog ACvoltage generated by a phase difference between a master AC voltage anda slave AC voltage fed back from the master trans and the slave transinto an analog DC voltage to at an initial condition or at an operatingcondition.
 33. The backlight driving apparatus as claimed in claim 32,wherein said protective controller compares the magnitude of an analogDC voltage fed back via the feedback portion with the reference voltageat an initial condition or at an operating condition to determinewhether there is an error at an initial condition or at an operatingcondition.
 34. The backlight driving apparatus as claimed in claim 33,wherein when the magnitude of the reference voltage is the same as theanalog AC voltage, the protective controller outputs an enable signal tothe master driver and the slave driver.
 35. The backlight drivingapparatus as claimed in claim 33, wherein when the magnitudes aredifferent from each other, then the protective controller outputs adisable signal to the master driver and the slave driver.